Environmental geology of the Summitville mine, Colorado

Although altered and mineralized rocks at Summitville mine in Colorado contain minimal amount of sulfide minerals, acid mine problems existed primarily because of the pervasive alteration of the surrounding rocks, through hydrothermal process, to highly siliceous and argillized rocks that are incapable of buffering acidic waters during weathering. The problems are compounded by the continued exposure of altered and mineralized rocks in open pit, heap leach pad and waste piles to oxygenated waters. Inadequate subsurface structural control and underground mine workings also greatly affect water quality and the location of acid mine drainage output. It is expected that with these initial results, geological studies on constrained acid-generation from ore and altered rocks will be pursued.